In recent years, there have been manufactured semiconductor memories of 64 MDRAM/0.25 μm (the minimum processing line width) in 8-inch wafer (200±4 mm: SEAJ specification). In addition, development of semiconductor memories of 256 MDRAM/0.18 to 0.25 μm is newly underway. In conventional technology development, there has been a trend that a storage capacity increases by about 4 times approximately every three years.
Profitability has been improved based on the general rule that, when shrinking (reduction of the minimum processing line width) in a design rule and an increase in wafer size are carried out simultaneously, the yield per wafer is increased by four times.
However, the simultaneous advancement of fining and an increased diameter of wafer size cause a problem such as an increased amount of money for equipment investment or extended development period. In particular, when the time for conversion from 8 inches into 300 mm has come, as the manufacture of 1 G DRAM becomes feasible with respect to the storage capacity, such a problem is currently the major concern.
In the case where a wafer size is changed from 8 inches to 300 mm, when a consistent line is constructed, it is expected that the amount of money for research & development will exceed 200,000,000,000 Yen, and that the development period requires two times longer than conventionally. As a result, an increased amount of money for equipment investment causes an increase in depreciation cost, and an extended development period causes an increase in running costs. As a result, the profitability of semiconductor device manufacturers would be lowered. In order to improve this, restriction of increased equipment cost, reduction of COO, improvement of equipment throughput or the like is required.
Conventionally, since reduction in the design rule and an increase in diameter of a wafer resulted in higher costs of manufacturing apparatus and raw materials including wafers, manufacturing lines were directed to fabricate a few limited types of product in rather large quantity.
However, according to the needs of, for example, a hybrid LSI or the like in which a plurality of constituent elements consisting of analog and digital circuits are formed on one substrate, a processing technology is required, which allows controllability over small quantity of production of many types of products.
A conventional manufacturing line originally restricts the type of semiconductor device to be manufactured. Thus, although the above conventional manufacturing line is suitable for mass-production such as DRAM, it becomes unable to correspond to processing steps that substantially differ from a predetermined processing step and substantial displacement change or modifications are required because of changes in the processing steps. Thus, the cost and man hours associated with changes becomes prohibitively high, and profitability expected for such an investment cannot be guaranteed.